Drying sponges



G. T. HART, JR

DRYING SPONGES Filed Dec. 51, 1955 Patented May 11, 1937 PATENT OFFICE scram name srouoas George '1. Hart. In, Lynn, Mara, auignor to United Shoe Machinery Corporation, Paterson, N. 1., a corporation oi New Jersey application December 31, 1935. Serial No. 58,951

I Claim.

This invention relates to methods of and apparatus for drying compressible articles and it is illustratively described herein in its application to the drying of sponges electrically, as by the utilization of an electrostatic field produced by currents of high frequency.

In the production of artificial sponges, some of which are manufactured of viscose or the like, it

is found necessary to remove an excess of moisture. When this drying is accomplished by circulating air around the blocks of sponge material, the difiiculty has been encountered that uneven shrinkage distorts the blocks of material, commonly producing a cupping clone or more of the broader faces. Before such sponges are marketed, the manufactured blocks are, after dry-.

ticle while thus compressed. Preferably, the lat:

ter is accomplished by the use of an electrostatic field so that the heating, as is well understood, occurs throughout the block and avoids to a large extent the formation of a crust upon the outer surface of the'block, such as would otherwise result were the sponge dried by the usual methods.

Another object of the invention is to provide a convenient and efiective apparatus for carrying out this method.

The illustrated apparatus, in accordance with sulated on their inner faces and between which the sponge may be positioned and means for moving one of said electrodes toward the other to compress the sponge positioned between them. 45 These insulated electrodes serve as part of an electrical drying means, and are also utilized for compressing the sponge and holding it in compressed condition during the drying operation.

These and other featuresv of the invention will be described in the following description, taken in connection with the accompanying drawing, in which Fig. 1 is an angular view of our novel apparatus. and a M Fig. 2 is an angular view oi the block of sponge features of the invention, comprises electrodes inmaterial, indicating by dash lines the extent to which such a block shrinks during the drying operation.

Qynthetic sponges which are sometimes manufactured from viscose need to be artificially dried before they are ready to be put on the market. During this drying operation, there is considerable shrinkage so that a block of sponge iii in a dry condition will become smaller by an amount indicated by the dash lines l2 in Fig. 2 during the drying and also distorted or cupped. When such a distorted, cupped body is subdivided into small pieces for marketing, there is considerable waste.

I have, therefore, provided for the drying of the sponges in a compressed condition, having found that a block of sponge which has been compressed substantially as much as it would normally shrink during the drying operation, does not become cupped or otherwise seriously distorted and may be subdivided into small pieces much more economically. To this end I dry the blocks of compressed sponge electrically by placing these blocks in an electrostatic field produced by high-frequency currents. This manner of producing heat in the moist blocks has the additional advantage that the heat is produced substantially evenly throughout the whole body of the sponge and that, therefore, there is little or no tendency for the formation of crust upon the outer surface of the block which would have to be removed before sale.

To aid in the production oi an electrostatic field, I have provided plates or electrodes H and it which, to prevent sparking between the plates andthe articles to be dried, are buried in blocks iii and of some insulating material such as bakelite, thereby insulating said plates on their inner or adjacent faces. Small corners of the plates project from the blocks of material and are provided with binding posts 22 so thatthey may be connected to the outlet terminals 24 of a high-frequency oscillator. This oscillator, illustrated diagrammatically as enclosed within a box 28, is provided with terminals 28 to which electric current may be supplied. It may be of any construction designed to produce high-frequency currentsof the order of five to fifty million cycles per second. Conveniently, a frequency of thirteen or fourteen megacycles may be employed. When such high-frequency currents are supplied to the apparatus, an electrostatic field will be set up between the plates l4 and i6, and this will, as is well understood, produce heat within the block of sponge ll so long as there is any moisture therein. When the moisture is substantially removed, the heating automatically ceases. Conveniently, these blocks l8 and 20 may be supported upon a base 30, the block l8 having a flange 32 by means of which it is secured to the base, while the block 20 is slidable along the base. The sponge l may conveniently be supported upor ribs 34 on the base and when the block 20 is moved toward the block l8, the sponge will be constricted or contracted to substantially the size which it will have after the shrinkage induced by thedrying operation has ceased.

To facilitate movement of the block 20 so as thereby to compress and partially collapse the sponge, I have provided toggle links 40, extending between the outer face of the block 20, and an abutment 42. These toggle links have crossbars 44' and 45 which are interconnected by means of a vertical strut 46, thus forcing the toggles to move together in producing a movement of the block 20 in parallel planes. Operation of the toggles is effected by means of a hand lever 48 pinned to a cross rod 50 which, in turn, is pinned to the ends of the two upper toggle links. These upper links have meeting faces 52 so that they will stay in a straightened position .slightly beyond dead center in opposition to two coiled springs 54 which are interposed between the block 20 and the abutment 42 and tend to pull this block away from-the work.

In the carrying out of the method, the plate l6 and its block 20 having been moved toward the operator by the springs 54 following depression of the hand lever 48, a block of sponge may be positioned between the two electrodes and the hand lever raised to compress the sponge. If power is then supplied to the terminals 28 of the high-frequency oscillator, an electrostatic field will be set up between the plates l4 and I6, and drying will be effected throughout the body of the sponge, substantially without cupping or other distortion of the sponge. 1

Having described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of drying compressible material such as sponges or the like liable to shrinkage sists in first compressing the sponge an amount substantially equal to the normal shrinkage which occurs during drying, and then producing heat electrically within the sponge.

4. The method of drying a block of sponge, which consists in applying pressure to opposite faces of the block thereby to constrict the sponge, and positioning the constricted sponge in an electrostatic field to cause heating within the sponge thereby to remove the moisture.

5. The method of drying blocks of sponge or the like which consists in partially collapsing the blocks, and then creating an electrostatic field around the contracted sponge to heat the same and dry it.

6. In an apparatus for drying sponges, a pair of electrodes insulated from contact with a sponge, and means interconnecting said electrodes for positively moving one electrode toward the other to compress a sponge positioned between them.

7. In an apparatus for drying sponges, a base, an electrode insulated on its inner face and mounted in fixed position on the base, another electrode also insulated on its inner face and movably mounted upon the base, and a toggle for moving said movable electrode to compress a sponge positioned between the electrodes.

GEORGE T. HART, JR. 

